Pazopanib in metastatic multiply treated progressive gastrointestinal stromal tumors: feasible and efficacious.

backgroundA median progression free survival (PFS) of 18-20 months and median overall survival (OS) of 51-57 months can be achieved with the use of imatinib, in metastatic or advanced gastrointestinal stromal tumor (GIST). Sunitinib and regorafenib are approved options for patients progressing on imatinib, but with markedly decreased survival. pazopanib is a broad spectrum TKI targeting KIT, PDGFR and VEGFR receptors and has shown promising activity in phase 2 trials in GIST.

methodsAll patients who received pazopanib for GIST between March 2014 and September 2015 in our institution were reviewed. Patients were assessed for response with CT or PET CT scans. Patients continued pazopanib until progression or unacceptable toxicity. Survival was evaluated by Kaplan Meier product method.

resultsA total of 11 consecutive patients were included in our study. Median duration of follow up was seven months. The median lines of prior therapy was 2 [1-5]. Partial response (PR) was observed in seven patients and two had stable disease (SD). Two patients died within one month of start of pazopanib. Five of ten patients had progressed during the study with eight patients still alive. The median PFS was 11.9 months and the median OS was not reached. Common adverse events seen were hand-foot-syndrome (HFS) in four patients, anemia in four patients and fatigue in three patients. Grade 3/4 adverse events were uncommon. Three patients required dose modification of pazopanib.

conclusionsPazopanib is a reasonably efficacious well tolerated TKI and can be explored as a treatment option in advanced GIST that has progressed on imatinib.